Fluoride
Monona Waterworks
Fluoride occurs naturally in surface and groundwater and is also added to drinking water by many water systems to prevent cavities and support oral health in people.
In 2015, the Department of Health and Human Services updated its recommendation of an optimal level of 0.7 parts per million, or ppm, added to drinking water based on the health benefits of tooth decay prevention. Studies have shown that fluoride added to community water systems at this level reduces dental cavities, especially in children.
And studies have conclusively shown that fluoride in toothpaste and mouthwash can also provide these benefits.
Read More.
Health Concerns
Although the HHS-recommended level of 0.7 ppm can help promote oral health in children and adults, this level is likely too high for bottle-fed babies. EWG recommends that caregivers mix baby formula with fluoride-free water.
And fluoride in water at higher levels can be detrimental for everyone, especially children.
Long-term ingestion of higher levels of fluoride in water increases dental fluorosis, which includes mottling, pitting and weakening of the teeth in children.
A 2024 authoritative assessment by the National Toxicology Program found that higher levels of fluoride exposure, such as drinking water containing more than 1.5 ppm of fluoride, are associated with lower IQ in children. The conclusion was based on studies in human populations outside of the U.S.
Affecting systems with naturally occurring fluoride, EPA’s maximum legal limit is set at 4 parts per million (ppm) to prevent skeletal fluorosis, a condition where bones become brittle and more susceptible to fracture. But these effects may occur at lower levels of exposure, raising concerns that the current limit may not adequately protect public health.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2018 | 0.677 ppm | 24 | 24 | 0.570 ppm - 0.830 ppm |
| 2019 | 0.679 ppm | 24 | 24 | 0.510 ppm - 0.830 ppm |
| 2020 | 0.657 ppm | 22 | 22 | 0.530 ppm - 0.870 ppm |
| 2021 | 0.569 ppm | 26 | 26 | 0.410 ppm - 0.731 ppm |
| 2022 | 0.632 ppm | 24 | 24 | 0.490 ppm - 0.840 ppm |
| 2023 | 0.545 ppm | 27 | 27 | 0.0851 ppm - 0.810 ppm |
ppm = parts per million
State, National, and Health Guidelines for Drinking Water
EPA Maximum Contaminant
Level (MCL): 4 ppm
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-01-30 | 364667001 | 0.656 ppm |
| 2018-01-30 | 364667001 | 0.670 ppm |
| 2018-02-13 | 366667001 | 0.640 ppm |
| 2018-02-13 | 366667001 | 0.674 ppm |
| 2018-03-05 | 369181001 | 0.696 ppm |
| 2018-03-05 | 369181001 | 0.830 ppm |
| 2018-04-02 | 373735001 | 0.674 ppm |
| 2018-04-02 | 373735001 | 0.690 ppm |
| 2018-05-07 | 379970001 | 0.703 ppm |
| 2018-05-07 | 379970001 | 0.710 ppm |
| 2018-06-20 | 389965001 | 0.659 ppm |
| 2018-06-20 | 389965001 | 0.690 ppm |
| 2018-07-19 | 395680001 | 0.650 ppm |
| 2018-07-19 | 395680001 | 0.730 ppm |
| 2018-08-03 | 398480001 | 0.675 ppm |
| 2018-08-03 | 398480001 | 0.740 ppm |
| 2018-09-19 | 409015001 | 0.570 ppm |
| 2018-09-19 | 409015001 | 0.633 ppm |
| 2018-10-24 | 416245001 | 0.600 ppm |
| 2018-10-24 | 416245001 | 0.675 ppm |
| 2018-11-06 | 418108001 | 0.653 ppm |
| 2018-11-06 | 418108001 | 0.710 ppm |
| 2018-12-05 | 422695001 | 0.592 ppm |
| 2018-12-05 | 422695001 | 0.720 ppm |
| 2019-01-15 | 427843001 | 0.618 ppm |
| 2019-01-15 | 427843001 | 0.730 ppm |
| 2019-02-20 | 432340001 | 0.699 ppm |
| 2019-02-20 | 432340001 | 0.830 ppm |
| 2019-03-07 | 434246001 | 0.741 ppm |
| 2019-03-07 | 434246001 | 0.760 ppm |
| 2019-04-03 | 438548001 | 0.676 ppm |
| 2019-04-03 | 438548001 | 0.720 ppm |
| 2019-05-08 | 444792001 | 0.660 ppm |
| 2019-05-08 | 444792001 | 0.790 ppm |
| 2019-06-05 | 449993001 | 0.694 ppm |
| 2019-06-05 | 449993001 | 0.770 ppm |
| 2019-07-08 | 455630001 | 0.599 ppm |
| 2019-07-08 | 455630001 | 0.610 ppm |
| 2019-08-28 | 466437001 | 0.619 ppm |
| 2019-08-28 | 466437001 | 0.660 ppm |
| 2019-09-05 | 467858001 | 0.663 ppm |
| 2019-09-05 | 467858001 | 0.770 ppm |
| 2019-10-16 | 476627001 | 0.510 ppm |
| 2019-10-16 | 476627001 | 0.627 ppm |
| 2019-11-07 | 480311001 | 0.613 ppm |
| 2019-11-07 | 480311001 | 0.740 ppm |
| 2019-12-04 | 484316001 | 0.570 ppm |
| 2019-12-04 | 484316001 | 0.622 ppm |
| 2020-01-09 | 488637001 | 0.710 ppm |
| 2020-01-09 | 488637001 | 0.870 ppm |
| 2020-04-13 | 500401001 | 0.662 ppm |
| 2020-04-13 | 500401001 | 0.760 ppm |
| 2020-05-05 | 503147001 | 0.636 ppm |
| 2020-05-05 | 503147001 | 0.760 ppm |
| 2020-06-08 | 508232001 | 0.530 ppm |
| 2020-06-08 | 508232001 | 0.579 ppm |
| 2020-07-06 | 512768001 | 0.612 ppm |
| 2020-07-06 | 512768001 | 0.650 ppm |
| 2020-08-05 | 518329001 | 0.636 ppm |
| 2020-08-05 | 518329001 | 0.850 ppm |
| 2020-09-02 | 523121001 | 0.610 ppm |
| 2020-09-02 | 523121001 | 0.626 ppm |
| 2020-09-16 | 525773001 | 0.600 ppm |
| 2020-09-16 | 525773001 | 0.645 ppm |
| 2020-10-15 | 531401001 | 0.560 ppm |
| 2020-10-15 | 531401001 | 0.650 ppm |
| 2020-11-02 | 533856001 | 0.636 ppm |
| 2020-11-02 | 533856001 | 0.670 ppm |
| 2020-12-01 | 537860001 | 0.570 ppm |
| 2020-12-01 | 537860001 | 0.635 ppm |
| 2021-01-05 | 542128001 | 0.645 ppm |
| 2021-01-05 | 542128001 | 0.690 ppm |
| 2021-03-01 | 549104001 | 0.462 ppm |
| 2021-03-01 | 549104001 | 0.680 ppm |
| 2021-03-01 | 549104001 | 0.462 ppm |
| 2021-03-01 | 549104001 | 0.680 ppm |
| 2021-04-05 | 554182001 | 0.481 ppm |
| 2021-04-05 | 554182001 | 0.720 ppm |
| 2021-04-23 | 557976001 | 0.484 ppm |
| 2021-04-23 | 557976001 | 0.530 ppm |
| 2021-05-03 | 559207001 | 0.551 ppm |
| 2021-05-03 | 559207001 | 0.590 ppm |
| 2021-06-03 | 564875001 | 0.580 ppm |
| 2021-06-03 | 564875001 | 0.731 ppm |
| 2021-07-12 | 571445001 | 0.460 ppm |
| 2021-07-12 | 571445001 | 0.500 ppm |
| 2021-08-02 | 575448001 | 0.420 ppm |
| 2021-08-02 | 575448001 | 0.429 ppm |
| 2021-09-07 | 581714001 | 0.625 ppm |
| 2021-09-07 | 581714001 | 0.660 ppm |
| 2021-10-01 | 587153001 | 0.631 ppm |
| 2021-10-01 | 587153001 | 0.640 ppm |
| 2021-11-02 | 592558001 | 0.410 ppm |
| 2021-11-02 | 592558001 | 0.569 ppm |
| 2021-12-02 | 596701001 | 0.541 ppm |
| 2021-12-02 | 596701001 | 0.610 ppm |
| 2022-01-03 | 600268001 | 0.568 ppm |
| 2022-01-03 | 600268001 | 0.660 ppm |
| 2022-02-04 | 604528001 | 0.600 ppm |
| 2022-02-04 | 604528001 | 0.602 ppm |
| 2022-03-04 | 608062001 | 0.623 ppm |
| 2022-03-04 | 608062001 | 0.720 ppm |
| 2022-04-01 | 611733001 | 0.626 ppm |
| 2022-04-01 | 611733001 | 0.690 ppm |
| 2022-05-03 | 616910001 | 0.670 ppm |
| 2022-05-03 | 616910001 | 0.673 ppm |
| 2022-06-01 | 622451001 | 0.679 ppm |
| 2022-06-01 | 622451001 | 0.840 ppm |
| 2022-07-05 | 628273001 | 0.490 ppm |
| 2022-07-05 | 628273001 | 0.622 ppm |
| 2022-08-08 | 635437001 | 0.578 ppm |
| 2022-08-08 | 635437001 | 0.630 ppm |
| 2022-09-01 | 640172001 | 0.657 ppm |
| 2022-09-01 | 640172001 | 0.740 ppm |
| 2022-10-03 | 645984001 | 0.567 ppm |
| 2022-10-03 | 645984001 | 0.620 ppm |
| 2022-11-04 | 651718001 | 0.572 ppm |
| 2022-11-04 | 651718001 | 0.600 ppm |
| 2022-12-05 | 655415001 | 0.540 ppm |
| 2022-12-05 | 655415001 | 0.596 ppm |
| 2023-01-05 | 659523001 | 0.525 ppm |
| 2023-01-05 | 659523001 | 0.560 ppm |
| 2023-02-01 | 662712001 | 0.551 ppm |
| 2023-02-01 | 662712001 | 0.650 ppm |
| 2023-03-02 | 666476001 | 0.488 ppm |
| 2023-03-02 | 666476001 | 0.600 ppm |
| 2023-03-17 | 668880001 | 0.0851 ppm |
| 2023-03-17 | 668879001 | 0.108 ppm |
| 2023-03-17 | 668944001 | 0.112 ppm |
| 2023-04-05 | 671640001 | 0.486 ppm |
| 2023-04-05 | 671640001 | 0.600 ppm |
| 2023-05-08 | 677000001 | 0.600 ppm |
| 2023-05-08 | 677000001 | 0.810 ppm |
| 2023-06-05 | 681714001 | 0.546 ppm |
| 2023-06-05 | 681714001 | 0.700 ppm |
| 2023-07-05 | 686706001 | 0.610 ppm |
| 2023-07-05 | 686706001 | 0.670 ppm |
| 2023-08-01 | 692125001 | 0.525 ppm |
| 2023-08-01 | 692125001 | 0.700 ppm |
| 2023-09-06 | 698631001 | 0.650 ppm |
| 2023-09-06 | 698631001 | 0.670 ppm |
| 2023-10-02 | 703590001 | 0.641 ppm |
| 2023-10-02 | 703590001 | 0.730 ppm |
| 2023-11-07 | 709480001 | 0.530 ppm |
| 2023-11-07 | 709480001 | 0.547 ppm |
| 2023-12-04 | 712836001 | 0.480 ppm |
| 2023-12-04 | 712836001 | 0.548 ppm |